In addition to Phaneuf, Ottawa acquired forwards Matt Frattin, Casey Bailey, Ryan Rupert and defense prospect Cody Donaghey. In return, the Maple Leafs received defenseman Jared Cowen, forwards Milan Michalek, Colin Greening and Tobias Lindberg, and the Senators' second-round pick in the 2017 NHL Draft.
Since Shanahan arrived as the new boss in Toronto, he slowly has made massive changes by replacing general manager Dave Nonis with Lou Lamoriello and coach Randy Carlyle with Mike Babcock, while also moving out the big contracts of underperforming players Phil Kessel, David Clarkson and now Phaneuf.
In moving Phaneuf to Ottawa, the Maple Leafs didn't have to retain any salary, which is a huge plus. They retained $1.2 million when they traded Kessel to the Pittsburgh Penguins over the summer.
Toronto did, however, add some salary for next season. According to GeneralFanager.com, Cowen ($3.1 million), Michalek ($4.0 million) and Greening ($2.65 million) are all signed through next season. Lindberg is also signed, but he's on an entry-level contract through the 2017-18 season.
Cowen, a towering defenseman who never found his footing in Ottawa, is the quick fix to replace Phaneuf. He has potential he hasn't come close to reaching yet.
Greening soon could have a role with the Maple Leafs or be sent to the Toronto Marlies of the American Hockey League. Michalek likely will have a role with the Maple Leafs when he's healthy. He's out indefinitely with a broken finger.
However, the key to the entire trade from Toronto's perspective is getting rid of Phaneuf's large cap charge. It gives the Maple Leafs flexibility in their potential pursuit of a big-ticket free agent either this summer or next.
In fact, it sure looks as if this trade is Toronto's clearest indication it plans to go all-in to sign Tampa Bay Lightning captain Steven Stamkos if he becomes an unrestricted free agent on July 1.
There may be holes in that plan, though, because there's no guarantee Stamkos will hit free agency or that he'll want to sign with Toronto. He has publicly stated his interest in staying in Tampa Bay and winning with the Lightning. He also has publicly stated he doesn't have a desire to go to a rebuilding team.